The disclosure relates to a radiation image detector with capability of automatic exposure detection (AED) and an AED method thereof.
Similar to a visible light image sensing panel, a radiation image detector utilizes a pixel array to sense an image light. Since the image light to be sensed by the radiation image detector is an X-ray, different sensing materials and mechanisms are adopted.
The image sensing mechanism of the radiation image detector is to generate electrons and holes by emitting the X-ray into a semiconductor sensing material. Specifically, the holes corresponding to each pixel are collected and converted through a circuit, so as to obtain pixel data of an image. The holes are collected to obtain positive charges, which correspond to the grayscale values of the pixels, such that the pixel array can form a digital X-ray radiation image.
Since the sensing material used by the radiation image detector is a photoconductive material for generating positive charges and negative charges, a dark current exists and results in issues regarding the background level, which will affect the accuracy of the sensed image. Besides, in the case of an inappropriate exposure time (for example, the exposure onset and cessation time points are not consistent with the activated time of the X-ray source), the image quality will also be affected.
How to improve the image sensing quality of the radiation image detector is one of the factors that should be taken into consideration for research and development.